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141.
Microsatellites, comprising tandemly repeated short nucleotide sequences, are ubiquitous in eukaryotic genomes. Mutations within microsatellites are frequent, altering their overall length by insertion or deletion of a small number of repeat units, with a rate as high as 10(-3) in humans. Despite their high mutability, stable allele frequency distributions are typically observed for microsatellites in humans as well as other primates, although the mechanism maintaining these stable distributions remains unclear. Previous studies have suggested that microsatellite mutations occur more frequently in longer alleles and favour expansion. Generalizing these results has been hindered because the sample sizes were small, only a small subset of alleles for any marker was studied and the direction of mutation (expansion or contraction) was not rigorously determined. Here we examine 236 mutations at 122 tetranucleotide repeat markers and find that the rate of contraction mutations increases exponentially with allele size, whereas the rate of expansion mutations is constant across the entire allele distribution. The overall rate of expansion mutations does not differ from that of contractions. Our findings offer an explanation for the stationary allele distribution of microsatellites. 相似文献
142.
Solar cells are attractive candidates for clean and renewable power; with miniaturization, they might also serve as integrated power sources for nanoelectronic systems. The use of nanostructures or nanostructured materials represents a general approach to reduce both cost and size and to improve efficiency in photovoltaics. Nanoparticles, nanorods and nanowires have been used to improve charge collection efficiency in polymer-blend and dye-sensitized solar cells, to demonstrate carrier multiplication, and to enable low-temperature processing of photovoltaic devices. Moreover, recent theoretical studies have indicated that coaxial nanowire structures could improve carrier collection and overall efficiency with respect to single-crystal bulk semiconductors of the same materials. However, solar cells based on hybrid nanoarchitectures suffer from relatively low efficiencies and poor stabilities. In addition, previous studies have not yet addressed their use as photovoltaic power elements in nanoelectronics. Here we report the realization of p-type/intrinsic/n-type (p-i-n) coaxial silicon nanowire solar cells. Under one solar equivalent (1-sun) illumination, the p-i-n silicon nanowire elements yield a maximum power output of up to 200 pW per nanowire device and an apparent energy conversion efficiency of up to 3.4 per cent, with stable and improved efficiencies achievable at high-flux illuminations. Furthermore, we show that individual and interconnected silicon nanowire photovoltaic elements can serve as robust power sources to drive functional nanoelectronic sensors and logic gates. These coaxial silicon nanowire photovoltaic elements provide a new nanoscale test bed for studies of photoinduced energy/charge transport and artificial photosynthesis, and might find general usage as elements for powering ultralow-power electronics and diverse nanosystems. 相似文献
143.
采用一种新型FBG应变计量测钢筋混凝土柱在受压过程中的表面应变,并与常规应变片量测方法进行比较.通过机械固定法将FBG应变计安装于立柱表面,并考虑温度对测量结果的影响,最终实现对混凝土结构表面应变的量测,并对其工作性能进行评价.试验结果表明,FBG传感器具有很高的线性度及可重复性,测量值与理论值及常规电阻应变片量测结果一致,为其应用于实际工程提供了依据. 相似文献
144.
Chonghua He Shicheng Su Fei Chen Di Huang Fang Zheng Wei Huang Jianing Chen Xiuying Cui Qiang Liu Erwei Song Herui Yao Yujie Liu 《科学通报(英文版)》2014,59(12):1326-1333
A previous study indicated that C–C chemokine(C–C motif)ligand 18(CCL18)is capable of inducing tumor cell invasion and metastasis by interacting with receptor membrane-associated phosphatidylinositol transfer protein 3(PITPNM3)in breast cancer cells.The present study aims to investigate the correlation between the PITPNM3 expression and metastasis in hepatocellular carcinoma(HCC).Real-time quantitative polymerase chain reaction and Western blot were performed to detect the expression pattern of PITPNM3 in patient samples and HCC cell lines.Wound-healing and transwell chamber assays were performed to assess the migration and invasiveness of HCC cells,and the activation of the signaling protein downstream of PITPNM3 was also detected by Western blot and immunofluorescence.The results revealed that PITPNM3 was upregulated in HCC tissue compared to matched normal liver tissue.Silencing the expression of PITPNM3 by specific siRNAs markedly attenuated the invasive and metastatic abilities of HCC cells,whereas the upregulation of PITPNM3 significantly increased HCC cell mobility.Furthermore,inhibiting the expression of PITPNM3 suppressed the activation of Pyk2,FAK,and Src,while overexpression of PITPNM3enhanced the phosphorylation of FAK and Src in HCC cells.Besides,suppression of Pyk2 can also impair the clustering of integrin.These results imply that PITPNM3 is a vital determinant of HCC migration and invasion. 相似文献
145.
A UNIFIED MODEL FOR SOLAR FLARES 总被引:1,自引:1,他引:0
Chen Pengfei Fang Cheng Ding Mingde Tang Yuhua 《南京大学学报(自然科学版)》1999,(4):496-499
Solarflaresareusuallyclassifiedintotwotypes,i.e.,compactandtwo-ribbonflares,whichwerethoughttorequirequitedifferentphysicalmechanisms[1].Duringtheeruptionoftwo-ribbonflares,denseplasmaloopsriseinthecoronaforover10hours,withtheirfoot-pointsseparating.… 相似文献
146.
By optical inspection of macro-etched metallography and electron back-scattered diffraction (EBSD) mapping, this paper analyzed the microstructure of austenitic stainless steel strips produced with an equal-diameter twin-roll strip caster. The results indicate that the microstructure of the strips includes two columnar zones with highly compact dendrites and one equiaxed zone. The characteristics, such as grain size and growing direction of columnar grains and equiaxed grains, were investigated. An additional transitional area with many finer grains between the columnar zone and the equiaxed zone was found. As shown in EBSD analysis, small angle boundaries exist both in the columnar zone and the equiaxed zone, although they are especially more in the transitional area. Additionally, some <111> twin boundaries were found in the microstructure of the strips. 相似文献
147.
A prediction model for Current Efficiency (CE) of low temperature aluminum electrolysis (LTAE) with the low molar ratio electrolyte of Na3AIF6-AIF3-CaF2-MgF2-LiF-Al2O3 system was investigated based on artificial neural network principles. The nonlinear mapping between CE of LATE and various electrolytic conditions was obtained from a number of experimental data and used to predictCE of LATE. The trained neural networks possessed high precision and resulted in a good predicting effect. As a result, artificial neural networks as a new cooperating and predicting technology provide a new approach to the further studies on low temperature aluminum electrolysis. 相似文献
148.
Carvalho CM Ramocki MB Pehlivan D Franco LM Gonzaga-Jauregui C Fang P McCall A Pivnick EK Hines-Dowell S Seaver LH Friehling L Lee S Smith R Del Gaudio D Withers M Liu P Cheung SW Belmont JW Zoghbi HY Hastings PJ Lupski JR 《Nature genetics》2011,43(11):1074-1081
We identified complex genomic rearrangements consisting of intermixed duplications and triplications of genomic segments at the MECP2 and PLP1 loci. These complex rearrangements were characterized by a triplicated segment embedded within a duplication in 11 unrelated subjects. Notably, only two breakpoint junctions were generated during each rearrangement formation. All the complex rearrangement products share a common genomic organization, duplication-inverted triplication-duplication (DUP-TRP/INV-DUP), in which the triplicated segment is inverted and located between directly oriented duplicated genomic segments. We provide evidence that the DUP-TRP/INV-DUP structures are mediated by inverted repeats that can be separated by >300 kb, a genomic architecture that apparently leads to susceptibility to such complex rearrangements. A similar inverted repeat-mediated mechanism may underlie structural variation in many other regions of the human genome. We propose a mechanism that involves both homology-driven events, via inverted repeats, and microhomologous or nonhomologous events. 相似文献
149.
Lu X Wang L Chen S He L Yang X Shi Y Cheng J Zhang L Gu CC Huang J Wu T Ma Y Li J Cao J Chen J Ge D Fan Z Li Y Zhao L Li H Zhou X Chen L Liu D Chen J Duan X Hao Y Wang L Lu F Liu Z Yao C Shen C Pu X Yu L Fang X Xu L Mu J Wu X Zheng R Wu N Zhao Q Li Y Liu X Wang M Yu D Hu D Ji X Guo D Sun D Wang Q Yang Y Liu F Mao Q Liang X Ji J Chen P Mo X Li D Chai G Tang Y Li X Du Z Liu X Dou C Yang Z Meng Q Wang D Wang R Yang J Schunkert H Samani NJ Kathiresan S Reilly MP 《Nature genetics》2012,44(8):890-894
We performed a meta-analysis of 2 genome-wide association studies of coronary artery disease comprising 1,515 cases and 5,019 controls followed by replication studies in 15,460 cases and 11,472 controls, all of Chinese Han ancestry. We identify four new loci for coronary artery disease that reached the threshold of genome-wide significance (P < 5 × 10(-8)). These loci mapped in or near TTC32-WDR35, GUCY1A3, C6orf10-BTNL2 and ATP2B1. We also replicated four loci previously identified in European populations (in or near PHACTR1, TCF21, CDKN2A-CDKN2B and C12orf51). These findings provide new insights into pathways contributing to the susceptibility for coronary artery disease in the Chinese Han population. 相似文献
150.
分析了船舶和海洋平台锅炉在运行中由于锅炉水不合格引起的结垢、腐蚀的原因,以及会产生的危害,介绍了在应用中较为实用的锅炉水处理方法和其工作原理。总结了为达到理想处理效果而采用的方案及在日常管理方面应注意的事项。 相似文献